 (defn volume-integrator
   [scene id]
   {:pre [(conf/volume-integrators id)]}
-  (append-singleton scene :volume-integrator (name id) {}))
+  (append-singleton scene :volume-integrator id {}))
 
 (defn renderer-slg
-  [scene {:keys [cpu? gpu? ]}]
+  [scene {:keys [cpu? gpu?]}]
   (append-singleton
    scene :renderer "slg"
    {:config

         (color? absorb) (optional color? absorb-hsb)
         (number? abs-scale) (number? abs-depth)]}
  (append
   scene :volumes (name id)
   {:__type type
    :fresnel [:float (if (keyword ior) (presets/ior-presets ior) ior)]
    :absorption [:log-color [(if absorb-hsb (col/hsb->rgb absorb-hsb) absorb)

  [scene id alpha]
  (if (< alpha 1.0)
    (material-mix
     scene id "__hidden__" (material-id id alpha) alpha)
    scene))

(defn material-matte
